Choosing ultra high resolution is a tradeoff. You'll obviously have to tone down the graphic workload per pixel versus 1080p.

That doesn't mean we have to settle for Quake level visuals at 1080p. Even a lowly HD7790 can do 1.8 TFLOPS, which works out to 3600 ops per pixel for 4k at 60fps. That's an oversimplification, but clearly there's enough horsepower to give decent visuals at 4k.